Rifabutin, a promising alternative to rifampin in the treatment of tuberculosis in HIV+ patients receiving protease inhibitors, will be studied in an intermittent regimen in this protocol. The objective is to determine the proportion of HIV+ patients with concurrent TB who demonstrate abnormal INH and rifabutin pharmacokinetics (PK). The study will also determine risk factors for the abnormal PKs, evaluate correlations between PK parameters and the occurrence of toxicity, and evaluate the correlation between the PK parameters and the efficacy of the treatment.